1. Field of the Invention
This invention relates to a pickup apparatus for a disk player, and more particularly to a pickup apparatus for optically reading-out information on a disk arranged in the disk player.
2. Description of the Related Art
A disk player for replaying a disk-shaped optical disk such as an LD comprises a pickup apparatus for optically reading-out information on a rotating disk. The pickup apparatus of this sort generally comprises a pickup, a light emitting portion, a half mirror, and a detecting portion. The pickup is for transmitting a light to the disk and for receiving the light reflected from the disk. The half mirror is a plate shape member for reflecting the light outputted from the light emitting portion and for transmitting the light to the pickup, that the light from the pickup permeate. The light permeating through the half mirror incidents on the detecting portion.
Concerning such a pickup apparatus, when the disk player is instructed to replay the disk, the light emitting portion outputs the light. The light is reflected on the half mirror, and it reaches the disk via the pickup. Then, the light is transmitted to the half mirror passing through the pickup after being reflected on the disk, and moreover, it permeates the half mirror and incidents on the detecting portion.
Besides such a pickup apparatus, there has already been proposed techniques disclosed in Japanese Patent Application Publication No. HEI 6-30165 and Japanese Patent Application Laid-Open Publication No. SHO 58-82212 as a conventional pickup apparatus.
The apparatus disclosed in Japanese Patent Application Publication No. HEI 6-30165 comprises a hologram used for miniaturizing and lightening the apparatus instead of a lens of the pickup and the like, and a light-leading member for implementing transmission of the light among the light emitting portion, the hologram, and the detecting portion. In this apparatus, the hologram, the light emitting portion, and the detecting portion are directly fixed to the light-leading member. Accordingly, in the case where such a light-leading member is fixed inside the apparatus, it is less necessary to consider an arrangement position of each member than the case of the above-mentioned apparatus wherein the half mirror is arranged separately from the light emitting portion and the like.
On the other hand, in the apparatus disclosed in Japanese Patent Application Laid-Open Publication No. SHO 58-82212, each member is arranged separately from each other, and the half mirror is fixed to the frame by the adhesive agent. Moreover, in this apparatus, in order to suppress a distortion of the half mirror caused by shrinkage of the adhesive agent during a cure thereof, the half mirror is supported with three points, which is the minimum number of point required for determining its position. Concretely, the half mirror is placed on the three projections extending upward from a flat base, and is fixed by the adhesive agent applied on an edge of each projection.
In the apparatus disclosed in Japanese Patent Application Laid-Open Publication No. SHO 58-82212, the half mirror is installed from the upper part to the frame. However, in such a structure, the above-mentioned projections must be formed so that an area whereat the both are adhered to each other can be minimized for preventing the distortion of the half mirror from occurring.
Moreover, when assembling this apparatus, the half mirror is installed so as to be placed on the three projections. Therefore, the three points are fixed at an approximately same time. Accordingly, in such a structure, it is difficult to determine the position of the half mirror while fine-tuning it to the frame.